Separation and characterization of oxaliplatin dinucleotides from DNA using HPLC-ESI ion trap mass spectrometry |
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Authors: | Shereen Mowaka Michael Linscheid |
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Institution: | (1) Department of Chemistry, Humboldt Universitaet zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany |
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Abstract: | Oxaliplatin is a third-generation platinum complex, and has a broad spectrum of antitumor activity. Such platinum complexes
with the DACH carrier ligand have recently received increasing attention since they show efficacy against cisplatin-resistant
cell lines. As the foremost indication of antitumor activity of platinum drugs is the formation of adducts with genomic DNA,
calf thymus DNA-oxaliplatin adducts were the major target in this study. Calf thymus DNA was incubated with oxaliplatin, resulting
in the formation of a large number of platinum-DNA adducts. Treated DNA was digested into the dinucleotides with a combination
of enzymes, namely, benzonase, alkaline phosphatase, and nuclease S1. Using a high-performance liquid chromatography, we carried
out the separation of individual platinum-DNA adducts which were concurrently identified using electrospray ionization ion
trap mass spectrometry (MS). Both 1,2-intrastrand and 1,2-interstrand cross-linked adducts were found; however, those of the
intrastrand nature have a considerably higher abundance than those of the interstrand cross-links. Among them, d(GpG)-oxaliplatin
was the most abundant bifuctional adduct. To a lesser extent, a few monofunctional adducts were detected as well. MS
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experiments served to ascertain the detailed structures of oxaliplatin adducts of dinucleoside monophosphates and of dinucleotides.
Figure Three-dimensional view of the d(GpG)-Pt(DACH) adduct of m/z 902 (a) and of the d(ApG)-Pt(DACH) adduct of m/z 886 (b). DACH 1,2-diaminocyclohexane, green phosphorus, red oxygen, light blue carbon, dark blue nitrogen, gray platinum
Abbreviations They are shown in Fig. 1 |
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Keywords: | Oxaliplatin DNA adducts Benzonase Nuclease S1 HPLC-ESI-MS Fragmentation |
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